Do you have kids? Because if you do, you understand it is a complicated balance between figuring out what they are mature/responsible enough to handle and what they are not. My son did not diagnose himself as being on the spectrum, nor was he excluded from the process because we were seeing some differences from neurotypical children. I cannot feel how his brain reacts to ADHD medication, but I can work with him to find a better one. When an acquaintances daughter had panic attacks, they did not consult me about it. SSRI's which were prescribed helped this little girl feel like a little girl. She was high strung and struggled with separation anxiety from her mom.
In some ways, I do think being trans is like a mental health challenge. Because I imagine it is challenging to not feel right in their own body/gender and I can guess this goes beyond just feeling off. I can never really understand, but I also do not have to. I simply do not need to understand why someone wants to change something about themselves to make themselves feel better. And the lengths people go to to endure this change to feel better is something that is very daunting. From surgery to medical, to wardrobe, changing fucking information with the government, altering social identities and crowds (which if you read Cialdini's work, you would know is fucking huge). The issue I see it, is that the people on the right, downplay this process and liken it to changing your shoes. We even had a scumbag in a wheelchair talking about kids going to school and having sex change operations at schools, which we all know was complete horseshit but the right never bothered to call this out. (Schools of course lack the budget, expertise, will, and authority to do something like that. They also can't give my kid an advil when she has a headache and for my son to carry an inhaler, I have to fill out several forms and get them all signed by physicians so he can keep an inhaler on him whenever he needs it for wheezing. )
But back to the commented I quoted. I would value the vote of my ASD child. He is probably more informed than many adults and certainly more compassionate and empathetic to others even with his diagnosis. He might not have the context or full history that comes with years, but he knows quite a bit less propaganda and quite a bit more facts, especially relative to my parents.